Slide-valve.



J. MILLER.

SLIDE VALVE.

APPLICATION FILED 110124, 1911.

1,084,354. Patented Jan. 13,1911

2 SHEETS-SHEET 1.

COLUMBIA PLANOURAPH C01, WASHINGTON, D. c,

J. MILLER.

SLIDE VALVE. APPLICATION rILEfi NOV. 24, 1911.

1,084,354. Patented Jan. 13, 1914.

2 SHBETS8HEET 2.

COLUMBIA PLANOYJRAPH :0, WASHINGTON. D c,

UNITED STATES PATENT OFFICE.

JOSEPH MILLER, OF CHICAGO, ILLINOIS, ASSIGNOR OF ONE-FOURTH T0 GEORGE A. VJOODMAN AND ONE-FOURTH T0 CHARLES A. GARSCADIN, BOTH OF CHICAGO,

ILLINOIS.

SLIDE-VALVE.

Specification of Letters Patent.

Patented Jan. 13, 1914.

Application filed. November 24, 1911. Serial No. 662,154.

To all whom it may concern:

Be it known that I, Josnrrr MiLLnn, a citi zen of the United States, residing at Chi cage, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Slide-Valves, of which the following is a specification.

This invention relates to slide valves for steam engines and aims to produce a valve of this general character which will materially increase the efficiency of engines equipped therewith over their efficiency when equipped with ordinary slide valves.

It is well known to steam engineers and others familiar with steam engines that at each stroke of the engine piston and after the exhaust is closed, a certain amount of steam is trapped in the cylinder which must be compressed as the piston continues its stroke, and that a considerable amount of the energy of the live steam admitted to the opposite end of the cylinder is expended in compressing this trapped steam. In order to delay compression, or, in other words, to continue the exhaust as long as possible the inside lap, particularly on fast running engines, is dispensed with and in some instances the slide valves are constructed to provide inside clearance, which, of course, delays compression, but also hastens release. Slide valves of the ordinary type, however, if constructed with inside clearance or little inside lap must provide more outside or steam lap in order that that portion of the valve traveling over the cylinder ports may present sutficient area to hold the port closed for an appreciable time after cut-off occurs to enable the expansive force of the steam to be utilized. It will thus be manifest that whatever advantages heretofore have been gained, in the ordinary types of slide valve, by providing inside clearance which lengthens exhaust and delays compression, have been sacrificed by the necessary provision of outside or steam lap which delays admission and hastens cut-01f.

My present invention aims to embrace all of the advantages of inside clearance without any of the disadvantages of excessive outside lap and this result is obtained by increasing the time of exhaust to delay compression until substantially the point of admission, without delaying admission or hastening cut-off.

The invention will be best understood by reference to the following description when considered in connection with the accompanying drawings illustrating one preferred embodiment thereof.

Referring to the drawings: Figure 1 is a longitudinal sectional view of a steam chest equipped with my invention. Fig. 2 is a similar view showing the parts in a different position. Fig. 3 is a transverse sectional view taken on the line 33 of Fig. 2, and, Fig. l is a longitudinal sectional view taken on the line 4l4t of Fig. 3.

On the drawings, 5 designates the cylinder of a steam engine of any preferred type within which the piston (i is adapted to reciprocate, said cylinder being provided with the usual ports '7 and 8 and with the exhaust port 9 from which the exhaust steam is discharged through the exhaust pipe 11. The steam chest 12 is positioned above the cylinder in the usual way, the ends of said steam chest being provided with openings having suitable packing glands 13 and 14 through which the valve stem 15 is adapted to work. This stem preferably extends through both ends of the steam chest, as shown, in order to balance the slide valve by equalizing the areas presented. to the steam pressure on both ends thereof.

The slide valve comprises a main valve 16 and an auxiliary valve 17 carried thereby. The main valve is fixed on the valve stem 15 between shoulders or collars 18 rigidly secured to the stem, while the auxiliary valve is slidably supported upon the top of the main valve, the extent of relative movement between the valves being limited by upwardly projecting portions or buffers 19 against which the auxiliary valve abuts. The main valve is provided with the centrally disposed exhaust passageway 21 which extends vertically through the valve body and is located over and communicates with the exhaust steam port 9. The auxiliary valve likewise has a centrally disposed passageway extending vertically therethrough and indicated by reference character 22. The passageways 21 and 22 in the main and auxiliary valves are always in communication with each other. A packing ring 23 composed of any suitable material and made square, round, or of any other desired shape, is arranged in a groove 2a provided on the upper face of the auxiliary valve and surrounding the central passageway 22. Expansion springs 25 or other preferred resilient means are interposed between the bottom of the groove 24 and the packing ring to hold said ring against the top plate of the steam chest so that an effective seal is produced between the interior ofthe valve and the live steam compartment surrounding the valve. The passageway extends entirely through the auxiliary valve not only for the purpose of lightening the same but also to permit any steam which may leak past the packing ring 23 to escape directly to the exhaust. The advantages of this construction will be obvious since, if a solid-top valve were employed the expansive force of the steam which might collect above the top would have a tendency to press down upon the valve thereby increasing its friction and impairing the efficiency of the device.

In addition to the centrally disposed exhaust passageway 21 the main valve 16 is provided with auxiliary passages 26 and 27 which extend entirely through the body of the valve from top to bottom as shown. These passages or ports are positioned. to register with the cylinder ports 7 and 8 after the inside edges of the main valve have passed inwardly beyond the ports and delay compression by providing a means of escape for the steam which would normally be trapped in the cylinder. This action will be apparent from an inspection of Fig. 2 wherein the inside edge of the main valve has passed inwardly beyond the port 8 but the steam is still exhausting from the port 8 through the passage 27 and the passage 22 in the auxiliary valve into the main exhaust passage 21. The exhaust will be continued until the passage 27 has passed inwardly beyond the port 8 and immediately after this position of the main valve has been reached the live steam will be admitted to the cylinder through the port 8 from the steam chest. In other words, the exhaust is continued or compression is delayed until substantially the point of admission is reached. In order that premature release may not take place through the passages 26 and 27 the auxiliary valve is constructed to alternately close the upper ends of these passages and prevent release until the inner edge of the main valve has moved to a position to open the cylinder port. This will be apparent from Fig. 2 wherein it will be observed that the upper end of the auxiliary passage 26 is closed by the auxiliary valve and the port 7 cannot be opened to permit release until the main exhaust passage 21 is brought into communication with the port by the outward movement of the inner edge of the main valve.

For the purpose of moving or shifting the auxiliary valve relatively to the main valve at the proper times I have provided an auxiliary valve operating mechanism which is adapted to move the auxiliary valve relatively to the main valve as the main valve approaches the limit of its stroke. \Vith this end in view the sides of the main valve are provided with studs 28 upon which are pivotally mounted the rocker members 29. These members have oppositely extending arms 31 terminating at their extremities in upwardly projecting portions 32 adapted to engage with the inclined faces 33 of the stationary cam blocks 3d fixed to the walls of the steam chest whereby the rocker members are rocked or tilted on their pivots. Each of the rocker members also has an upwardly extending arm 35 provided with an elongated slot 36 which embraces a stud 37 formed on the side of the auxiliary valve 17. hen the main valve approaches the end of its stroke the rocker member is rocked to move the auxiliary valve from the position shown in full lines in Fig. 1 to the position shown in dotted lines thereby closing the passage 27 and opening the passage 26. It will be understood that the auxiliary valve travels back and forth in the steam chest with the main valve and that the additional motion or the movement of the auxiliary valve relatively to the main valve takes place only when the main valve approaches the end of its stroke and the movement is in the same direction that the main valve is traveling.

In order to obviate the necessity of a lubricant beneath the main valve 1 have provided the bed or bottom wall of the steam chest with a series of transversely extending grooves or pockets 38 in which the steam is trapped beneath the valve as the valve slides thereover. The expansive force of the trapped steam in these pockets tends to raise the valve from its seat thereby reducing the friction and eliminating the necessity of artificial lubrication. The pockets or grooves may be of any preferred shape or contour but I have found that the best results are obtained by making the pockets relatively narrow so that the steam will not readily escape therefrom as the valve is reciprocated. The number and arrangement 1 of the pockets, of course, may be varied to meet the exigencies of any particular construction.

The operation of my invention is briefly as follows: Assuming that the parts are in the position shown in full lines in Fig. 1, the piston 6 at that time is traveling forwardly or to the right, as indicated by the arrow, and the main valve has reached the limit of its forward movement. The rocker member has been tilted by the forward cam block 34: to move the auxiliary valve into its extreme forward position thereby closing the passage-26 and opening the passage 27. Steam is being admitted to the cylinder through the port 7 and exhaust is taking place through the port 8, the main exhaust passage 21 and the exhaust port 9. The slide valve now begins to move rearwardly or to the left, the first action being to cut off the admission at the port 7. The piston then travels under expansion and exhaust continues through the port 8 and the main exhaust passage 21 until the inner edge of the main valve overlaps the inner edge of the port 8. At this point the exhaust would be shut oil in an ordinary slide valve and the steam remaining in the cylinder in front of the piston would have to be compressed. To eliect this compression would require the expenditure of considerable energy, which, in my present invention, the compression being eliminated and the exhaust continued may be utilized in performing useful work. Immediately after the inner edge of the valve has passed beyond the inner edge of the port 8 the parts are in the position shown in Fig. 2 from which it will be observed that the steam in front of the cylinder is permitted to exhaust through the auxiliary passage 2'? and this exhaust will continue until the lower end of the passage 27 has passed inwardly beyond the inner edge of the port 8 at which time, or substantially at this time, the outer edge of the valve will overlap the port and permit admission of live steam. It will thus be manifest that exhaust is continued and compression is delayed until substantially the time of admission and the energy which has heretofore been expended in compressing the dead steam in front of the cylinder is conserved and utilized for useful purposes. During the travel of the slide valve and until after direct communication is established between the main exhaust passage 21 and the port 7 the upper end of the passage 26 is closed by the auxiliary valve as shown in Fig. 2, so that release is prevented until the proper time. As the main valve approaches the limit of its stroke the extension 32 on the rear arm 31 of the rocker member is brought into engagement with the cam surface of the rear stationary cam block 84: and the auxiliary valve is thereupon moved relatively to the main valve into the position shown in dotted lines in Fig. 1, opening the passage 26 and closing the passage 27. During the travel of the valve in the forward direction the exhaust is continued through the passage 26 until substantially the time of admission in the same manner that the exhaust was continued from the port 8 through the passage 27 when. the valve was traveling in the rearward direction. It will thus be apparent that I have provided a valve which lengthens the time of exhaust and delays compression until substantially the point of admission, thereby permitting practically complete exhaust from in front oi the piston, delaying compression, thereby increasing the mean eitective pressure and consequently the horsepower of the engine.

While I have shown and described a preferred embodiment of my invention it will be obvious that various changes in the size, shape, proportion and arrangement of the various parts may be resorted to without departing from the spirit of the invention or sacrificing any of the material advantages thereof.

I claim:

1. In a slide valve mechanism, the combination of a main valve, an auxiliary valve carried thereby and movable relatively thereto, and means for automatically moving said auxiliary valve relatively to the main valve and in the direction of travel of the main valve near the completion of each travel.

2. In a slide valve mechanism, the combination of a main valve provided with auxiliary exhaust ports, an auxiliary valve for moving said auxiliary ports, and mechanical means for controlling said auxiliary valve longitudinally of the main valve to permit exhaust through said auxiliary ports substantially to the time of admission.

3. In a slide valve mechanism, the combination of a. main valve ha "ing a main exhaust passage and auxiliary exhaust passages, an auxiliary valve carried by and movable longitudinally of said main valve, and mechanical means -for moving said auxiliary valve to permit exhaust through said auxiliary passages into the main exhaust passage until substantially the point of admission.

4-. In a slide valve mechanism, the combination of a main valve, an auxiliary valve carried by and movable relatively to said main valve, and means operable only when the main valve approaches the end of its stroke for moving said auxiliary valve relatively to the main valve and in the direction of travel of said main valve.

5. In a slide valve mechanism, the combination of a main valve provided with a main exhaust passage and auxiliary passages, an auxiliary valve carried by said main alive and movable longitudinally thereon for controlling said auxiliary passage, and means actuated by movement of the main valve for positively operating said auxiliary valve to alternately open and close said auxiliary passages.

('3. In a slide valve mechanism, the combination of a main valve having a main exhaust passage and auxiliary exhaust passages, a slide valve carried by said main valve for opening and closing said auxiliary passages, means mounted on said main valve for operating said auxiliary valve, and devices for engaging and actuating said means Q when the main valve approaches the limit of its movement.

7. In a slide valve mechanism, the combination of a main valve provided with a main exhaust passage and auxiliary exhaust passages, an auxiliary valve adapted to alternately close said auxiliary passages and establish communication between said passages and the main exhaust passage of the main valve, a rocker member pivoted on said main valve and operatively connected with said auxiliary valve, and stationary means adapted to engage and operate said member when the main valve approaches the end of its stroke for actuating said auxiliary valve to alternately open and close said auxiliary passages.

8. In a slide valve mechanism, the combination of a main valve, an auxiliary valve carried thereby and movable longitudinally thereon,ineans on said main valve for limiting the relative movement of said auxiliary valve, an operating device mounted on said main valve and connected with said auxiliary va ve, and stationary cam blocks mounted in the path or" travel of said device for moving said auxiliary valve relatively to the main valve when the main valve approaches the limit of its movement.

9. in a slide valve mechanism, the combination or" a main valve having a main exhaust passage xtending therethrough, an auxiliary valve mounted on said main valve and having an opening therethrough communicating with said exhaust passage, and a resilient packing rin carried by said auxiliary valve to form a seal between the top of said valve and the steam chest, the opening through said auxiliary valve and the exhaust passage in the main valve permitting the escape of any steam passing said packing ring.

10. in a slide valve mechanism, the combination of a main valve, and a seat over which said valve travels, said seat being provided with a plurality of grooves or steam pockets in which the steam is trapped beneath the valve.

11. In a slide valve mechanism, the combination of a main valve provided with auxiliary exhaust ports, an auxiliary valve for controlling said auxiliary ports, means moving the two valves simultaneously throughout the greater part of each stroke, and auxiliary means for accelerating the movement of the auxiliary valve near the end f the stroke of the main valve.

12. In a slide valve mechanism, the combination of a main valve, an auxiliary valve mounted on said main valve, said auxiliary valve having a longitudinal dimension less than the longitudinal dimension of the main valve, and means for moving said auxiliary valve from adjacent the rear end of said valve considered in the direction of travel of the valve to adjacent the front end of the valve near the completion of each travel of said valve.

JUSEPH MILLER. Witnesses VAN E. FREEMAN, J. L. GERRITY.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

